Kernel Breakage Research Articles

An innovative walnut cracker: Self-grading and multi-station extrusion mechanism with high efficiency.

The walnut cracking process is the most critical and delicate step for achieving high-quality kernels. The traditional method for cracking (manually) is labor-intensive, time-consuming, and tedious. The existing cracking approaches are low production efficiency and serious walnut kernel breakage. Increasing cracking efficiency with minimum kernel breakage has been a challenging issue in the preliminary processing of walnuts. Therefore, this study develops an innovative walnut cracker with self-grading and multi-station extrusion, combined with theoretical investigation and experiment verification. First, a statistical analysis of walnut physical properties was conducted, including dimensions, shell thickness as well as shape characteristics. The mechanical properties of walnut cracking were examined by a series of experiments. Based on mechanical theory, a grading mechanism was designed for preliminary processing before walnut cracking. Then a shaftless screw conveying mechanism and an extrusion cracking mechanism were developed. To evaluate the cracker's performance, a comprehensive examination was carried out. The experiments yielded impressive results, with a grading rate of 87.3%, a shell-breaking rate of 91.50%, and a kernel-exposed rate of 84.72%. These outcomes signify a substantial improvement in production efficiency while minimizing kernel breakage. The developed walnut cracker plays a crucial role in walnut processing and kernel extraction, thereby elevating economic value. PRACTICAL APPLICATION: A self-grading multi-station extrusion walnut cracker is developed, which includes a grading mechanism with a shaftless screw conveyor and a grid-type trommel screen for conveying and classifying walnuts. This cracker can adapt to different walnut varieties by changing the gap-adjusting guide to control the breaking gap. Compared to similar extrusion-type walnut crackers, the developed cracker not only incorporates preliminary classification but also exhibits superior performance. HIGHLIGHTS: A novel multi-station extrusion mechanism for walnuts cracking is developed. The cracker can accommodate various walnut sizes for self-grading and screening. The design with semi-arc plates converts extrusion force into alternating stress. The shell-breaking rate and kernel-exposed rate achieves 91.50% and 84.72%.

Prediction method for maize kernel impact breakage based on high-speed camera and FEM

Processes such as threshing and processing determine the subsequent storage, nutritional value, and economic value of maize kernels. The breakage characteristics of maize kernels in threshing and processing machinery are unknown, which greatly limits the need for new developments in low-loss threshing. In this paper, the breakage characteristics of maize kernels under different impact postures and impact velocities were investigated by a combination of FEM and bench tests. The results showed that the breakage evolution rules of kernel breakage modes were the result of stress concentration and energy conversion. The maize kernel with side posture had the smallest critical breakage velocity of 22.5 m/s for breaking into pieces. A breakage probability model for predicting the degree of maize kernel breakage was proposed, and the energy and velocity thresholds provided a method for the digital design of breakage reduction performance of maize threshing machinery and detection performance of impact breakage machinery.

Real-Time Detection Technology of Corn Kernel Breakage and Mildew Based on Improved YOLOv5s

In order to solve low recognition of corn kernel breakage degree and corn kernel mildew degree during corn kernel harvesting, this paper proposes a real-time detection method for corn kernel breakage and mildew based on improved YOlOv5s, which is referred to as the CST-YOLOv5s model algorithm in this paper. The method continuously obtains images through the discrete uniform sampling device of corn kernels and generates whole corn kernels, breakage corn kernels, and mildew corn kernel dataset samples. We aimed at the problems of high similarity of some corn kernel features in the acquired images and the low precision of corn kernel breakage and mildew recognition. Firstly, the CBAM attention mechanism is added to the backbone network of YOLOv5s to finely allocate and process the feature information, highlighting the features of corn breakage and mildew. Secondly, the pyramid pooling structure SPPCPSC, which integrates cross-stage local networks, is adopted to replace the SPPF in YOLOv5s. SPP and CPSC technologies are used to extract and fuse features of different scales, improving the precision of object detection. Finally, the original prediction head is converted into a transformer prediction head to explore the prediction potential with a multi-head attention mechanism. The experimental results show that the CST-YOLOv5s model has a significant improvement in the detection of corn kernel breakage and mildew. Compared with the original YOLOv5s model, the average precision (AP) of corn kernel breakage and mildew recognition increased by 5.2% and 7.1%, respectively, and the mean average precision (mAP) of all kinds of corn kernel recognition is 96.1%, and the frame rate is 36.7 FPS. Compared with YOLOv4-tiny, YOLOv6n, YOLOv7, YOLOv8s, and YOLOv9-E detection model algorithms, the CST-YOLOv5s model has better overall performance in terms of detection accuracy and speed. This study can provide a reference for real-time detection of breakage and mildew kernels during the harvesting process of corn kernels.

Characteristics of Damage to Brown Rice Kernels under Single and Continuous Mechanical Compression Conditions.

During the rice milling process, single and continuous compression occurs between brown rice and the processing parts. When the external load exceeds the yield limit of brown rice, brown rice kernels are damaged; with an increase in compression deformation or the extent of compression, the amount of damage to the kernels expands and accumulates, ultimately leading to the fracture and breakage of kernels. In order to investigate the mechanical compression damage characteristics of brown rice kernels under real-world working conditions, this study constructs an elastic-plastic compression model and a continuous damage model of brown rice kernels based on Hertz theory and continuous damage theory; the accuracy of this model is verified through experiments, and the relevant processing critical parameters are calculated. In this study, three varieties of brown rice kernels are taken as the research object, and mechanical compression tests are carried out using a texture apparatus; finally, the test data are analysed and calculated by combining them with the theoretical model to obtain the relevant critical parameters of damage. The results of the single compression crushing test of brown rice kernels showed that the maximum destructive forces Fc in the single compression of Hunan Early indica 45, Hunan Glutinous 28, and Southern Japonica 518 kernels were 134.77 ± 11.20 N, 115.64 ± 4.35 N, and 115.84 ± 5.89 N, respectively; the maximum crushing deformations αc in the single compression crushing test were 0.51 ± 0.04 mm, 0.43 ± 0.01 mm, and 0.48 ± 0.17 mm, respectively; and the critical average deformations αs of elasticity-plasticity deformation were 0.224 mm, 0.267 mm, and 0.280 mm, respectively. The results of the continuous compression crushing test of brown rice kernels showed that the critical deformations αd of successive compression damage formation were 0.224 mm, 0.267 mm, and 0.280 mm, and the deformation ratios δ of compression damage were 12.24%, 14.35%, and 12.84%. From the test results, it can be seen that the continuous application of compression load does not result in the crushing of kernels if the compression deformation is less than αd during mechanical compression. The continuous application of compressive loads can lead to fragmentation of the kernels if the compressive deformation exceeds αd; the larger the compression variant, the less compression is required for crushing. If the compression deformation exceeds αc, then a single compressive load can directly fragment the kernels. Therefore, the load employed during rice milling should be based on the variety of brown rice used in order to prevent brown rice deformation, which should be less than αd, and the maximum load should not exceed Fc. The results of this study provide a theoretical reference for the structure and parameter optimisation of a rice milling machine.

Fabrication of Palm Nut Cracking Machine and Performance Evaluation of Cracked Nuts Parameters as Influenced by Cultivars

Palm Nut Cracker Machine is mainly needed for the Palm Nut seeds. Palm Nut is very hard in nature and very tough to break manually with hand; hence in industrial production of palm oil a palm nut cracker machine that is able to break the palm nuts into the small pieces is usually necessary. Therefore, the objective of this paper was to fabricate a palm nut cracking machine and evaluate its performance of cracked nuts parameters as influenced by cultivars using standard methods. Data obtained shows that optimum crack efficiency of 97% was obtained at shaft speed 2600 rpm dura cultivar of 8% MCdb, 7 kg feed weight, 91% crack efficiency was obtained for tenera cultivars at 6% MCdb and 5 kg feed weight at the same shaft speed, while, crack efficiency of 87% was observed for pisifera cultivar at 6% MCdb, feed weight of 7 kg and operational speed of 2200 rpm. Optimum kernel breakage ratio % of 14.66, 21.93, and 17.24 % occurred at the experimental cracking of palm nuts dura, tenera and pisifera cultivars with corresponding feed weights 7, 5 and 6 kg, respectively. On weightier feed rates and shaft speeds, crack efficiency of machine was higher for the oil Palm nuts cultivars at lower moisture content.

A Study of the Distribution of the Threshed Mixture by a Double Longitudinal Axial Flow Corn Threshing Device

In order to determine the distribution pattern of the threshed mixture in the double longitudinal axial flow threshing device, single-factor experiments were conducted on the self-developed experimental platform for the double longitudinal axis threshing device. The experimental factors included drum speed, threshing clearance, and feed rate. The variations in the distribution of the threshed material along the axial and radial directions were examined. The results indicate that the mixed material after threshing exhibits uneven distribution both axially and radially. Along the axial direction, the mass of corn kernels initially increases and then decreases and is predominantly distributed in the front one-third section of the drum. Meanwhile, the mass of corn cobs continuously increases. In the radial direction, the mass of corn kernels and cobs is higher in the middle and on both sides, with the corn kernels being most concentrated in the middle and the corn cobs mostly on the sides. Combining the corn kernel breakage rate and the unthreshed rate, the optimal operating conditions were determined as follows: a drum speed of 400 r/min, a concave clearance of 50 mm, and a feed rate of 16 kg/s.

Breakage behavior of corn kernels subjected to repeated loadings

Studying the breakage behavior of corn kernels subjected to repeated compressive events, including at low frequency and low strain rate, are important for the development of breakage models for prediction of kernel breakage in handling and processing machines. The main purpose of this study was to identify the breakage behavior and mechanism of weakening of corn kernels under repeated loadings as affected by their moisture content and kernel thickness. Corn kernels at four moisture content levels (8.20%, 11.95%, 16.00%, 20.02%) and in four thickness ranges were subjected to repeated compressive loading between two parallel steel plates in quasi-static regime at a constant loading rate of 2 mm/min (strain rates from 4.7 × 10−3 to 1.0 × 10−2). Conducted experiments allow to observe the different grain breakage patterns, identify the crack initiation and its development, describe the weakening of kernels by changes in the total specific energy, plastic and elastic deformation energies, and the number of loading cycles to break (breakage probability) the kernels. The results indicate that the breakage models describing the damage and weakening of grains in terms of changes in the total and strain energy or changes in the stiffness can be used for understanding the effect of moisture content and thickness on breakage of corn kernels.

Changes in Intergranular Air Properties and Chemical Parameters of Short-term Stored Bulk Shelled Corn with Slightly High Moisture Content

Objective: This study is to determine the main parameters influencing the storage of shelled corn with slightly high moisture content (MC) so that its quality can be maintained. Methods: The intergranular air properties and chemical changes was determined in 4,169 tonnes of shelled corn bulk with an average MC of 15.3% and a height of 5m, which was stored for 90 days in a large warehouse in Shandong Province, China, from winter to early spring. The intergranular air property parameters were calculated with self-compiled software. Results: Fans were used to achieve temperature-equalizing aeration at a low rate (5.87m3/h/t) after warehousing, which decreased the bulk temperature from 6.8 to 4.7℃. Afterwards, with the increase in ambient temperature, the surface-layer grain temperature increased drastically, while that of the bottom layer increased slowly and those of the middle layers increased even more slowly. The minimum and mean cumulative dry-bulb, wet-bulb and dew-point temperatures (DPT) increased in the order of middle layer˂ bottom layer˂ surface layer. Free fatty acid content, kernel breakage percentage, water adsorption rate, gelatinization enthalpy, peak enthalpy, and fatty acid profiles (C16:0, C18:0, C18:3n3, C20:0 and C20:1) were significantly related to the cumulative intergranular air properties of grain bulk. Conclusion: The above physio-chemical parameters were significantly influenced by the minimum and mean cumulative values of relative humidity, Humidity ratio and DPT in the bulk, and can be used to evaluate the quality of shelled corn with slightly high MC during short-term storage.

Factors, Harms, and Control of Corn Kernel Breakage: A Review

Corn kernel breakage is an important cause of corn losses. Beginning at harvest, corn kernels are broken by collisions with farm machinery and equipment, drying induces increased kernel breakage susceptibility, and equipment transfers and grain loading generate collisions between corn kernels and with equipment, increasing the amount of broken kernels. Meanwhile, broken kernels increase the risk of insect damage, mold and mildew, as well as aggravate segregation during warehousing, which is detrimental to the safety and quality of corn storage. The causes of corn kernel breakage from harvest to storage are summarized, the water content is a key factor in the post-production quality and quantity of corn, the research results on kernel breakage in recent years are summarized, and suggestions are made for the research related to the reduction of corn kernel breakage rate.

Detection of the Corn Kernel Breakage Rate Based on an Improved Mask Region-Based Convolutional Neural Network

Real-time knowledge of kernel breakage during corn harvesting plays a significant role in the adjustment of operational parameters of corn kernel harvesters. (1) Transfer learning by initializing the DenseNet121 network with pre-trained weights for training and validating a dataset of corn kernels was adopted. Additionally, the feature extraction capability of DenseNet121 was improved by incorporating the attention mechanism of a Convolutional Block Attention Module (CBAM) and a Feature Pyramid Network (FPN) structure. (2) The quality of intact and broken corn kernels and their pixels were found to be coupled, and a linear regression model was established using the least squares method. The results of the test showed that: (1) The MAPb50 and MAPm50 of the improved Mask Region-based Convolutional Neural Network (RCNN) model were 97.62% and 98.70%, in comparison to the original Mask Region-based Convolutional Neural Network (RCNN) model, which were improved by 0.34% and 0.37%, respectively; the backbone FLOPs and Params were 3.09 GMac and 9.31 M, and the feature extraction time was 206 ms; compared to the original backbone, these were reduced by 3.87 GMac and 17.32 M, respectively. The training of the obtained prediction weights for the detection of a picture of the corn kernel took 76 ms, so compared to the Mask RCNN model, it was reduced by 375 ms; based on the concept of transfer learning, the improved Mask RCNN model converged twice as quickly with the loss function using pre-training weights than the loss function without pre-training weights during training. (2) The coefficients of determination R2 of the two models, when the regression models of the pixels and the quality of intact and broken corn kernels were analyzed, were 0.958 and 0.992, respectively. These findings indicate a strong correlation between the pixel characteristics and the quality of corn kernels. The improved Mask RCNN model was used to segment mask pixels to calculate the corn kernel breakage rate. The verified error between the machine vision and the real breakage rate ranged from −0.72% to 0.65%, and the detection time of the corn kernel breakage rate was only 76 ms, which could meet the requirements for real-time detection. According to the test results, the improved Mask RCNN method had the advantages of a fast detection speed and high accuracy, and can be used as a data basis for adjusting the operation parameters of corn kernel harvesters.

Development and Performance Evaluation of a Hand Operated Maize Sheller

Maize is a popular food crop of the world. After harvest, maize is shelled traditionally by small holders of farms. This method has not proved to be effective due to drudgery attached, kernel breakage and poor shelling capacity. Over time, motorized shellers have been introduced to address the challenges faced by processors; they have not gained widely adoption due to unaffordable cost of owning one. There is the need to design a cost effective and eco-friendly solution that will suit the need of subsistence farmers in the industry. This work focuses on development of a hand-operated maize sheller. A major component is the lever arm fitted to a ball bearing to transfer rotational motion to stripping chute. The machine uses the principle of abrasion to shell maize. Model (Y=54.92+ 0.248 X1-2.68 X2 ± 1.187) obtained from evaluation reveals that shelling capacity is a function of two predictors, speed (X1) and moisture content (X2). For every unit increase in cranking speed at a particular moisture content (23.2%, 18.5% or 14%) shelling capacity increases considerably. When the experiment is run at much lower moisture content (18.5%) shelling capacity increases significantly. The machine reached highest shelling capacity (60 kg h-1.) at lowest moisture content (14%) and highest speed (120 rpm). The machine was developed at affordable cost of $61. Shelling efficiency is also a function of speed and moisture content at which it is processed. For this condition, maximum shelling efficiency is achieved at lowest moisture content possible (14%) and terminal speed of 80 rpm. Mechanical damage resulted when the speed and moisture content are inconsiderably high. The machine is suitable for use by small and medium scale processors; it can efficiently replace the manual shelling methods as it is affordable, less stressful and easy to maintain.

玉米籽粒疲劳损伤寿命统计分析

It is urgent to study the damage mechanism of corn kernels and find ways of reducing the rate of kernel breakage in mechanical threshing. This paper, by studying the mechanical curves and deformation characteristics of corn kernels with different moisture contents, points out the brittle mechanical characteristics of corn kernel damage fracture with low moisture content, and clarifies the the variation law of mechanical properties of kernels with moisture contents. The experimental data of fatigue load - fatigue life curves of corn kernels with different moisture contents were described by the power function equation. At the same time, the fatigue life and damage characteristics of kernel with different moisture content were analyzed, and the accuracy of the fitting equation was verified. Through mathematical statistical analysis, the normal distribution curve of fatigue life was fitted, and the variation law of normal distribution curve with moisture content and fatigue load was determined.

Development and performance evaluation of shelling unit of power operated groundnut decorticator

Decortication is an operation in which the shells of groundnut are separated with least damage to kernels and it involves a lot of drudgery when done manually. Decortication of groundnut is an essential operation prior to use of kernel in any form. Kernel breakage is an important parameter for developing a suitable groundnut decorticator. As a result, a research to develop a power operated groundnut decorticator as an upgrade to the existing 1 hp power operated commercially available groundnut decorticator was undertaken in the Department of Farm Machinery and Power Engineering, CAET, Junagadh during 2021–2022. To start with, the moisture content and feed rate of existing cast iron blade type groundnut decorticator were optimized for better performance for the variety GJ-21. Thereafter, the performance of rubber padded blade, wooden blade and rasp bar type blade of groundnut decorticator was studied and compared. From the analysis of data, it was found that the optimized moisture content and feed rate of groundnut pods for getting better performance of existing cast iron blade type decorticator were respectively in the range of 9.5 % (w.b.) and 90-95 kg/h. Similarly, power operated groundnut decorticators, it was found that there was 94.0 %, 92.8 % and 90.4 % decorticating efficiency in rubber padded blade, wooden blade and rasp bar type blade, respectively. Breakage per cent was found 3.91 %, 5.66 % and 7.80 % in developed power operated groundnut decorticator for rubber padded blade, wooden blade and rasp bar type blade, respectively.

Effects of cushion box and closed let-down ladder usage on impact damage to corn kernel during handling.

The main purpose of this study was to evaluate the effects of the cushion box and closed let-down ladder usage in minimizing mechanical damage to corn kernels during free fall. Kernels from a single lot of cultivar KSC 705 were evaluated for percentage of breakage using three drop methods (free fall, with cushion box, and with closed let-down ladder) at five different moisture contents (10%, 15%, 20%, 25%, and 30%), and three drop heights (5, 10, and 15 m). The results showed that the drop methods had a significant effect on the breakage sensibility of kernels. Sample kernels dropped without a ladder (free fall) had a significantly higher average percentage breakage of 13.80%. In the use of the cushion box, the average kernel breakage was calculated to be 11.41%, which was decreased by about 17% more than the free fall. Sample kernels dropped with the closed let-down ladder had a lower average breakage of 7.26%, which showed that the closed let-down ladder significantly helped to reduce mechanical damage to corn kernels by about 47% comparing free fall and by about 37% than the use of the cushion box. The amounts of kernel damage increased significantly with increasing drop height and decreasing moisture content, but the use of the cushion box and closed let-down ladder systems somewhat reduced the adverse effect of the above factors. To minimize mechanical damage to kernels as they fall into the bin, a grain let-down ladder should be installed in the bin so that it can receive kernels from the filling spout with minimum damage. Empirical models were developed for the dependency of damage to corn kernels due to the impact caused by free fall on the drop height and moisture content at different drop methods.

Compression and Fungal Heat Production in Maize Bulk Considering Kernel Breakage

Breakage in maize kernels and vertical pressure in grains lead to the uneven distribution of grain bulk density, which easily causes undesired problems in terms of grain storage. The objective of this study was, therefore, to determine the compression and heat production of the whole kernel (WK) and half kernel (HK) under two different loadings, i.e., 50 and 150 kPa, in maize bulk. An easy-to-use element testing system was developed by modification of an oedometer, and an empirical–analytical–numerical method was established to evaluate fungal heat production, considering kernel breakage and vertical pressure. Based on the experimental results, it was found that breakage induced larger compression; the compression of HK was 62% and 58% higher than that of WK at 50 kPa and 150 kPa, respectively. The creep model of the Hooke spring–Kelvin model in series can be used to accurately describe the creep behavior of maize bulk. Fungi and aerobic plate counting (APC) were affected significantly by the breakage and vertical pressure. APC in HK was 19 and 15 times that of WK under 150 and 50 kPa, respectively. The heat released by the development of fungi was found to be directly related to the APC results. The average temperatures of WK and HK under 150 and 50 kPa were 11.1%, 9.7%, 7.9%, and 7.6% higher than the room temperature, respectively. A numerical method was established to simulate the temperature increase due to fungi development. Based on the numerical results, heat production (Q) by fungi was estimated, and the results showed that the Q in HK was 1.29 and 1.32 times that of WK on average under 150 and 50 kPa. Additionally, the heat production results agreed very well with the APC results.

Design and development of a palm kernel nut cracking unit

The object of this research is the cracking of the nuts of oil palm (Elaesis guineensis). The oil palm tree is one of the greatest economic assets a nation can have, provided its importance is realized and fully harnessed. After the oil extraction of palm oil from the palm fruits, virtually all methods involved in palm kernel nut cracking both in traditional and small-scale exist in scattered or separate units of operations. Hence, this research focused on designing a palm nut kernel cracking unit incorporating a separator in form of a screen to separate cracked palm kernel nut shell from kernel. The result shows that there were significant difference (p≤0.05) among the moisture content of the palm nuts, shaft speed of the machine and weight (feed rate), having a significant difference between: – moisture content of the palm nut and the shaft speed of the cracker; – moisture content and feed rate; – shaft speed and feed rate. There exist interaction between cracked, uncracked shell, damaged, undamaged kernel, and palm kernel nut breakage ratio. While, there was no significant difference among interaction between moisture content, shaft speed and feed weight. The result also indicated that for the highest speed of 1,800 rpm at a feed rate of 700 kg/h for all moisture contents, the cracking efficiency was between10 to 90 %, which implies that the kernel cracking efficiency increases with an increase in machine speed. However, it was observed that higher cracking efficiency was at the cost of higher kernel damage for all cracking speeds and feed rates, which is a problem. The kernel breakage ratio ranged from 1.040–7.85 for all feed rates and moisture contents. The kernel breakage ratio increased with moisture content and cracking speed but decreases with feed rate weight.

Study of corn kernel breakage susceptibility as a function of its moisture content by using a laboratory grinding method

The rate of corn kernel breakage in the grain combine harvesters is a crucial factor affecting the quality of the grain shelled in the field. The objective of the present study was to determine the susceptibility of corn kernels to breakage based on the kernel moisture content in order to determine the moisture content that corresponds to the lowest rate of breakage. In addition, we evaluated the resistance to breakage of various corn cultivars. A total of 17 different corn cultivars were planted at two different sowing dates at the Beibuchang Experiment Station, Beijing and the Xinxiang Experiment Station (Henan Province) of the Chinese Academy of Agricultural Sciences. The corn kernel moisture content was systematically monitored and recorded over time, and the breakage rate was measured by using the grinding method. The results for all grain samples from the two experimental stations revealed that the breakage rate y is quadratic in moisture content x, y=0.0796x2−3.3929x+78.779; R2=0.2646, n=512. By fitting to the regression equation, a minimum corn kernel breakage rate of 42.62% was obtained, corresponding to a corn kernel moisture content of 21.31%. Furthermore, in the 90% confidence interval, the corn kernel moisture ranging from 19.7 to 22.3% led to the lowest kernel breakage rate, which was consistent with the corn kernel moisture content allowing the lowest breakage rate of corn kernels shelled in the field with combine grain harvesters. Using the lowest breakage rate as the critical point, the correlation between breakage rate and moisture content was significantly negative for low moisture content but positive for high moisture content. The slope and correlation coefficient of the linear regression equation indicated that high moisture content led to greater sensitivity and correlation between grain breakage and moisture content. At the Beibuchang Experiment Station, the corn cultivars resistant to breakage were Zhengdan 958 (ZD958) and Fengken 139 (FK139), and the corn cultivars non-resistant to breakage were Lianchuang 825 (LC825), Jidan 66 (JD66), Lidan 295 (LD295), and Jingnongke 728 (JNK728). At the Xinxiang Experiment Station, the corn cultivars resistant to breakage were HT1, ZD958 and FK139, and the corn cultivars non-resistant to breakage were ZY8911, DK653 and JNK728. Thus, the breakage classifications of the six corn cultivars were consistent between the two experimental stations. In conclusion, the results suggested that the high stability of the grinding method allowed it to be used to determine the corn kernel breakage rates of different corn cultivars as a function of moisture content, thus facilitating the breeding and screening of breakage-resistant corn.

A combined experimental and DEM approach to optimize the centrifugal maize breakage tester

Three centrifuge discs (straight, oblique, and curved) of a centrifugal maize breakage tester were investigated experimentally using discrete element method (DEM) simulation. Bonded particle model (BPM) was used to simulate the breakage behavior of maize kernels. A set of bond parameters was calibrated by comparing stiffness and rupture force of the kernel obtained from a uniaxial compression test. The breakage pattern of the kernels consisted of local disintegration and fragmentation at different impact velocities. The simulations revealed that the average velocity and breakage susceptibility (BS) were significantly affected by the rotational speed of the disc and increased linearly with an increase in the rotational speed. The BS was also significantly affected by the interaction of rotational speed and disc structure. The simulation results were the same as the experimental results, indicating that the BPM model provided an accurate representation of the kernel breakage and flow behavior in the breakage tester.

Effect of kernel breakage on the fermentation profile, nitrogen fractions, and in vitro starch digestibility of whole-plant corn silage and ensiled corn grain

The objective of this experiment was to analyze the effect of kernel breakage on the fermentation profile, nitrogen fractions, and ruminal in vitro starch digestibility of whole-plant corn silage and ensiled corn grain. Whole corn plants were harvested, and ears were separated from the forage portion and shelled. Corn kernels were either left intact or broken manually using a hammer. The remaining forage portion of the corn plants was chopped. Samples of the intact and broken kernels were stored for 0 or 30 d in quadruplicate vacuum pouches. Remaining intact and broken kernels were each reconstituted with the chopped forage portion of the corn plant to simulate whole-plant corn forage and were also stored for 0 or 30 d. In kernels separated from whole-plant corn silage, kernel form had no effect on zein protein concentrations. However, it was observed that in vitro starch digestibility at 7 h increased with ensiling only in kernels that were broken. When corn kernels were ensiled alone, concentrations of soluble crude protein and ammonia nitrogen increased with ensiling to a greater extent when kernels were broken. Finally, fermentation of ensiled corn grain was enhanced when kernels were broken. Overall, this study gives insight into the importance of kernel breakage to improve starch digestibility in corn silage through means other than a reduction in particle size and opens the door for continued investigation into the proteolytic activity occurring in the silo.

Difference in corn kernel moisture content between pre- and post-harvest

The harvest method of shelling corn (Zea mays L.) kernels in the field decreases labor costs associated with transporting, drying and threshing the crop. However, it was previously found that the kernel moisture content increased after field harvest, which decreased the value of corn kernels. To identify the reasons underlying the increase, we conducted a multiyear and -area trial in the Huang-Huai-Hai Plain, China and performed a staged-harvest test at several phases of kernel dry-down. The test investigated a range of parameters such as the kernel moisture content pre- and post-harvest, the kernel breakage rate, the amount of impurities, and the moisture content of various other plant tissues. An analysis of 411 pairs of pre- and post-harvest samples found that kernel moisture content after harvest was 2.2% higher than that before harvest. In the staged-harvest test, however, a significant increase was only observed when the kernel moisture content before harvest was higher than 23.9%. The increase in post-harvest kernel moisture content was positively associated with the pre-harvest kernel moisture content, breakage rate and impurity rate. Typically, at harvest time in this region, there is a significant fraction of immature crops with a high moisture content, resulting in kernels that are prone to breakage or impurities that ultimately lead to increases in water content after harvest. Therefore, we suggest using hybrids that quickly wither late in the growing stage. Additionally, farmers should delay harvest in order to minimize the pre-harvest kernel moisture content and thus reduce breakages and impurities, thereby improving the quality of kernels after harvest and the efficiency of corn kernel farming in China.